Nowadays, water mats are commercially available for use in daily life, and when a water mat is laid on a bed, sofa, or the like, it not only gives comfort, but also works as a tool for physical therapy. Such a water mat generally has a hermetically sealed cavity constituted by two layers of a film material, and into the cavity, water is injected to form a water mat. In some of the conventional water mats, a heater or cooler is installed in the cavity for heating or cooling the water to provide a hot or cold compress. Examples include a super conductive warm water mat as disclosed in Patent document 1. However, in service, the water mat may be broken through, being pierced by a pointed substance, or burst open, being depressed with a large pressure, resulting in the cavity leaking, which makes the water mat unusable, thus the water mat generally has a short service life. In addition, because of the flowability of water, the water mat has a slightly poor stability, and gives an uncomfortable feeling of rocking.